Spraying device in combination with a differential control valve



SPRAYING DEVICE IN COMBINATION WITH June 26, 1951 c; J. HACHMEISTER r, 2,558,531

- A DIFFERENTIAL CONTROL VALVE Filed Dec. 22, 1947 2 Sheets-Sheet 1 H I 257 4 2 I 3 at $7 I 5 1310677227 fiearyefffacmezszer June 26, 195'] G. J. HACHMEISTER 2,558,681

SPRAYING DEVICE IN COMBINATION WITH A DIFFERENTIAL CONTROL VALVE J/fazveqqs Patented June 26, 1951 SPRAYIN G DEVICE IN COMBINATION WITH A DIFFERENTIAL CONTROL VALVE George J. Hachmeister, Des Plaines, Ill., assignor to Dav-is Regulator Company, Chicago, 11]., a corporation of Illinois Application December 22, 1947, Serial No. 793,181

3 Claims.

My invention relates to improvements in differential control valves, and has for one object to provide a differential control element well adapted to control the operation of fluid-operated pumps and the like.

Other objects will appear from time to time in the specification and claims.

In. connection with the use of a spray gun for spraying heavy liquids such as tar, creosote and the like, experience has been that the air dis.- charged through the gun nozzle to entrain, discharge and spray the liquid is not adequate to drain the liquid from. the source of supply. So

the practice has arisen of associating with the gun and the liquid supply reservoir an air-operated motor which drives a pump to force the heavy liquid into the air stream and present to the atomizing and conveying air a continuous supply of the heavy liquid.

It happens, however, that such guns are not continuously operated, and so when the air is; turned off and the gun stops working, the practice has been to allow the air motor and pump to continue to operate. This builds up an excess pressure in the liquid supply line and may cause the accumulation of an excess mass of the liquid in the nozzle. Then, when the gun is turned on again, this excess mass of liquid is: discharged all at once and thus makes for waste, improper distribution and the like.

My differential control valve is adapted to automatically turn on and oif the supply of air to the air motor so that when the operator closes the air valve controlling the nozzle and stops the operation of the gun, the supply of air to theair motor is automatically cutoff, the pump stops, and no excess liquid is accumulated.

I have illustrated only so much of the mechanism as is necessary to illustrate the control. The details of the nozzle, pump, motor, storage reservoir, etc., where shown at all, are shown only diagrammatically.

My invention is illustrated more or less diagrammatically in the accompanying drawings, wherein:

Figure 1 is a perspective view of an apparatus with which my difierential control valve is used;

Figure 2 is a section through the control valve along the line 22 of Figure 3;

Figure 3 is a section along the line 33 of v Figure 2.

Like parts are indicated by like characters in the specification and drawings.

I is an air reservoir, 2 an air compressor driven by a motor 3, 4 a pipe leading from the compressor to supply compressed air to the reservoir. 5 is a liquid supply tank adapted to contain creosote, grease, oil or other heavy liquid to be sprayed, 6 a pump associated with the tank, driven by an air motor 1, 8 a conduitv leading from the tank to the pump, of such size that the material may flow freely from the tank to the pump.

9 is a spray gun, 10 an air hose leading from the air reservoir to the spray gun 9, H and air control valve which may be manipulated to control the supply of air from the reservoir to the gun. I2 is a liquid supply hose between the tank and the gun and terminating in the nozzle thereof in the usual manner so that liquid discharged from the hose [2 will be entrained by the compressed air rushing out through the nozzle of the gun. There is no separate operator-controlled valve for the liquid at the gun.

I3 is a pipe leading from the air reservoir l to the automatic control valve housing l t. I5 is a pipe leading from the control valve housing l4 to the air motor housing 1. H5 is a discharge passage from the air motor to atmosphere.

Air is supplied to the spray gun 9 through pipe. l3, housing M and hose I9, and when there is presented to that air in the gun 9 a continuing supply of liquid, the air will atomize and spray tains, in efi'ect, three separate chambers.

such liquid, discharging it from the gun to the work. At the same time the air passing from the air reservoir I through the air control valve l4 and pipe I5 to the air motor will operate the pump to supply the liquid to the gun for atomization and spraying.

The differential control valve housing con- Supply chamber receives air through the hose l3. Discharge chamber 2! discharges air on its way to the air motor through the hose i5. 22 is a partition wall separating chambers 29' and 2|, containing a valve aperture 23/, adapted to be closed by a renewable disc valve 24 on valve stem 25 and on hollow spring sleeve 26. Spring sleeve 26 and stem 25 are threaded together, disc 24 being compressed by the collar 21. Sleeve 26 contains a spring 28 subjected to pressure tend-- ing to seat the valve by the threaded cap 29. The spring pressure is sufficient to overcome the pressure of air in the chamber 20 and seat the valve to prevent air discharge. 3!] is the control chamber. It is divided into two areas by the flexible diaphragm 3i engaged on one side by a movable plate 32 rigidly mounted on the stem 25. A passage 33 leads from the chamber 20 through ports 34 and 35 to the opposite sides of the diaphragm 3|. The port 34 is permanently Air is also admitted to the air supply chamber,

20 and to both sides of the diaphragm 3|. under pressure admitted to the top of the dia phragm tends to force the diaphragm down, un-

seat the valve 24, permit air to pass out through the air motor, operate it, and supply the liquid to the gun. Air is, to be sure, also admitted to the underside of the diaphragm 3| through the controlled passage 35, but such air immediately escapes through the pipe 10 through the air control valve. Such escape is more rapid than the entry of the controlled air supply through the passage'35, and so the diaphragm 3| forces the valve 24 into the open position to permit con tinued operation of the airmotor.

If, however, the operator closes the air con trol valve, air cannot escape from the underside of the diaphragm 3|, and the air entering in through the controlled passage 35 soon equalizes pressure on both sides of the diaphragm 3| and the spring 28, then closes the valve 24, shutting off air supply to the motor so that no liquid is supplied to the gun during the time that air isair under pressure escapes from below the dia-,

phragm, the valve is opened to supply air to the motor, and the supply of liquid to the spray nozzle is resumed.

I claim:

1. In combination a spray gun, a source of atomizing air under pressure therefor, means comprising a pump and an air-operated :pum'pactuating motor for positively feeding to the gun a continuous supply of liquid to be sprayed, means for manually controlling the supply of atomizing air to the gun, a control housing, a passage therein adapted to receive air under pressure and supply such air to the motor, a valve in the passage, a control chamber in the housing, a movable wall in the control chamber, an operating connection between the wall and the valve whereby movement of the wall actuates the valve, supply passages in the housing adapted to conduct air under pressure to the control chamber on both sides of the partition, an exhaust passage leading from the control chamber on one side of the partition to thegun, the manual control means being adapted to simultaneously control the supply of atomizing air to the gun and the discharge of air from the exhaust passage.

2. In combination a spray gun, a source ofatomizing air under pressure therefor, means comprising a pump and air-operated pumpactuating motor for positively feeding to the gun a continuous supply of liquid to be sprayed, means for manually controlling the supply of atomizing air to the gun, a control housing, a passage therein adapted to receive air under pressure and supply such air to the motor, a valve in the passage, a control chamber in the housing, a movable wall in the control chamber, an operating connection between the wall and the valve whereby movement of the wall actuates the valve, supply passages in the housing adapted to conduct air under pressure to the control chamber on both sides of the partition, an exhaust passage leading from the control chamber on one side of the partition to the gun, the manual control means being adapted to simultaneously controlling the supply of atomizing air to the gun and the discharge of air from the exhaust passage, the partition being adapted to move to valve-opening position responsive to the air pressure thereon when air is allowed to escape through the exhaust passage.

3. In combination a spray gun, a source of atomizing air under pressure therefor, means comprising a pump and an air-operated pumpactuating motor for positively feeding to the gun a continuous supply of liquid to be sprayed, means for manually ccntrolling the supply of atomizing air to the gun, a control housing, a passage therein adapted to receive air under pressure and supply such ir to the motor, a valve in the passage, a control chamber in the housing, a movable wall in the control chamber, an operating connection between the wall and the valve whereby movement of the wall actuates the valve, supply passages in the housing adapted to conduct. air under pressure to the control chamber on both sides of the partition, an exhaust passage leading from the control chamber on one side of the partition to the gun, the manual control means being adapted to simultaneously controlling the supply of atomizing air to the gun and the discharge of air from the exhaust passage, the partition being adapted to move to valve-opening position responsive to the air pressure thereon whenair is allowed to escape through the exhaust passage, and yielding means adapted to return the partition to valve-closing position when the manual control valve is closed.v

GEORGE J. HACHD/IEISTER.

REFERENCES CITED The following references are of record in the file of this patent:

' UNITED STATES PATENTS 

